Aggregation Optimization of Cathode Interlayer via Incorporating Cellulose Enables High-Performance Organic Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Controlling molecular aggregation and packing in small-molecule cathode interlayer (CIL) materials is crucial for high-performance organic solar cells (OSCs).
• The perylene diimide (PDINN) molecule exhibits strong aggregation, leading to excessive crystallinity and negatively impacting film morphology and charge transport in OSCs.

Purpose of the Study:

• To develop a strategy to mitigate the aggregation of small-molecule CILs, specifically PDINN, to improve OSC performance.
• To investigate the effectiveness of a hydroxyl-induced anti-aggregation approach using hydroxypropyl cellulose (HPC).

Main Methods:

• Introducing hydroxypropyl cellulose (HPC) into the PDINN solution to create a hydroxyl-induced anti-aggregation effect.
• Evaluating the impact of the HPC-modified CIL on the performance of organic solar cells using PM6/Y6 and D18/L8-BO active layers.

Main Results:

• The introduction of HPC achieved a balance between film-forming quality and material aggregation.
• Significant increases in short-circuit current density (Jsc) and fill factor (FF) were observed in devices with the HPC-modified CIL.
• Power conversion efficiency improved from 17.38% to 18.25% for PM6/Y6 and from 18.45% to 19.73% for D18/L8-BO.
• Enhanced thickness tolerance of the HPC hybrid interface was demonstrated.

Conclusions:

• The hydroxyl-induced anti-aggregation strategy using HPC is a simple and effective method to address aggregation issues in small-molecule CILs.
• This approach significantly enhances the performance of organic solar cells and shows promise for other active layer systems.
• The findings contribute to the commercial development of organic solar cells by improving CIL material processing and device efficiency.